Elastic modulus reflects the ability of wood to resist deformation. The existing longitudinal vibration method plays an important role in the determination of elastic modulus of wood. To simplify the detection system and facilitate measurement, a novel method for measuring the elastic modulus of wood has been proposed, utilizing the longitudinal vibration excitation and electromechanical admittance (EMA) response of dual lead zirconate titanate (PZT) patches coupled with the specimen. To verify the effectiveness of the proposed method, theoretical derivation, finite element simulation and experimental research were carried out respectively. The theoretical derivation results show that the first-order longitudinal vibration mode frequency of the beam specimen coupled with dual PZT patches can be extracted through the real part of EMA response. Simulation results of six kinds of wood specimens show that the dual PZT patch transducer can effectively excite the first-order longitudinal vibration mode of the specimen, the main peak that corresponds to the first-order longitudinal vibration mode of the specimen exists in the EMA response, and the relative errors of the measurement results are less than 0.35

A new method for the determination of the dynamic modulus of elasticity (Ed) of pine wood, based on the transverse vibration excitation and electromechanical impedance (EMI) response of the lead zirconate titanate (PZT) transducer is proposed. The influence of the length to thickness ratio of the pine specimen on the measurement accuracy was studied through modal simulation analysis. Based on the results of the modal simulation, the size of the pine specimen was optimized, and the scanning frequency range of the EMI response was determined. On this basis, the EMI simulation and test of the pine specimen coupled with a PZT patch were carried out to verify the effectiveness of the novel method. The impedance simulation results of three kinds of pine specimens show that a unique and significant formant appears in the real part of each EMI response curve, and the maximum relative errors of the rectangular PZT patch and circular PZT patch are 1.34% and 1.81%, respectively. The impedance test results of three kinds of pine specimens indicate that the maximum relative errors of the rectangular PZT patch and circular PZT patch are 1.41% and 1.68%, respectively, compared with the corresponding results obtained by the traditional transverse vibration method. Simulation and experimental results verify the validity of the proposed method for the elastic modulus determination of pine wood.

提出了一种基于压电陶瓷和小波包分析的木梁纵向裂纹损伤检测方法.首先,在木梁纵向裂纹两侧表面粘贴压电陶瓷薄片,分别用于应力波激励和响应信号接收;然后,对响应信号进行小波包分解和能量计算,以小波包能量作为损伤指数进行木梁纵向裂纹的损伤程度识别.有限元仿真结果表明:随着木梁纵向裂纹深度增加,检测信号的小波包能量逐渐减小,初步验证了所提方法的有效性.试验研究与仿真结果一致,进一步验证了所提方法的有效性.

A damage detection and localization method for wooden beams was proposed based on the modal strain energy (MSE) change and evidence fusion. The fused damage indicator was deduced using the first three mode shapes of the wooden beams before and after damage. The finite element modal analysis of the free-supported undamaged and damaged wooden beams with different damage severities at one or two locations was performed. The first three mode shapes were extracted from the corresponding modal analysis, with which the damage indicator based on the MSE change and the fused damage indicator of each damage case were computed. The simulation results show that the fused damage indicator accurately detected and located the damage with different severities at one or two locations. Finally, the modal test was completed using the same damage cases as the finite element simulation. The frequency functions of the whole beam were first obtained, with which the first three experimental mode shapes were then acquired, and the damage indicator based on the MSE change and the fused indicator were further computed. The test results verified the validity and reliability of the proposed damage indicator.

切屑碎料在管道沉积甚至造成主管道堵塞是在木竹加工企业除尘系统中时常发生的问题,而且沉积的碎料时常夹带有磁性金属杂质.采用人工清理沉积物,费工费时,而利用除尘系统高速气流或压缩空气清理,可能因粉尘集聚静电电荷的放电或金属杂质与管壁撞击产生可诱发粉尘爆炸的火花.针对除尘系统管道沉积物的清除与除铁,提出了一种自适应变径的、具有沉降碎料及管道堵塞清除与除铁功能的管道机器人,使用SolidWorks设计了其机械结构与模型,研发了基于Wi-Fi通信的上下位机协同作业的控制系统,以期为木竹加工行业上述问题的解决提供一种有效、安全的途径.

针对触觉传感检测的实际需求,基于STM32单片机,采用分档分压与恒流源相结合的方法设计了一种压阻式柔性压力传感器阵列信号采集系统;基于串口通信技术设计了计算机信号读取与分析系统.设计开发的系统可以实现传感器阵列信号的实时采集、分析和存储,系统稳定性较好.采用标准电阻对研制的信号采集系统进行了性能检验,系统测量阻值与标准阻值的误差在1％以内,表明设计的信号采集系统满足压阻式柔性压力传感器阵列的检测需求.

在大学教育中,生产实习是其重要的教学实践环节,对学生未来就业有着重要的影响.就木材科学与工程专业而言,其生产实习更是与学生就业紧密相关.在木材科学与工程的生产实习教学实践中,学生的实践能力可以得到很大程度的培养.但是根据实际调查,木材科学与工程生产实习的总体质量还有待提高,其生产实习教学实践的亟需改革.本文就当前木材科学与工程专业生产实习的现状进行分析,提出了该专业生产实习的改革实践的建议.

生产实习是提升应用型人才培养质量的有效途径,能够强化学生的实际应用能力,使学生适应当前社会的发展,提升学生的综合素养.然而,在木材科学与工程专业的生产实习中还存在一些问题,因此,调整人才培养的方案、 教学内容与方法,提高生产实习的整体水平是当前的重要任务.文章主要阐述了生产实习培养应用型人才的重要性,分析了木材科学与工程专业培养应用型人才的生产实习的问题,并提出有效策略.

针对强化木地板自动包装线的特点,提出了一种基于PLC的包装线控制系统设计方法.在对包装线中自主研制装置控制系统设计的需求分析基础上,根据控制的逻辑要求,给出了基于S7-200PLC的I/O分配表和控制系统软件设计顺序功能图.根据S7-200 PLC的联网性能特点,采用计算机和Profibus总线实现了包装线的集成控制.

针对国内强化木地板包装主要依靠人工完成的现状,提出了一种强化木地板自动包装生产线设计方案.总结了强化木地板包装工艺流程,给出了强化木地板自动包装生产线总体设计方案,并分析了其工作流程.在此基础上,对强化木地板自动包装生产线中关键装置的设计方案进行了研究.

介绍了浸渍纸层压木地板生产线产品装卸载、包装和检验等过程自动化装备的功能与特点.与人工操作相比,自动化包装线可显著提高生产的效率与精度,延长生产线持续运转时间,新型装备还可完成组件添加和产品凑配等工艺性功能.企业应根据自身规模与主机装备水平选择合适的包装装备.

In china,the planting area of fir is large,and the number of small-diameter fir log is large. In order to improve the utilization rate and use value of small-diameter fir log,a new technique for preparing thin board by use of small diameter fir log is studied. Small-diameter fir log is processed into hexagonal prism,and then the hexagonal prisms are processed into large-section hexagonal prism glulam or rectangular glulam. The glulam is made into thin board by means of slicing or saw-ing,and used in the field of wood furniture,wood floor,wood doors and windows,interior and exterior decoration.

Small diameter logs should be sawn based on the shapes to increase the outturn. In this study,a log image detection and cutting system was designed accordingly. The log image acquisition and processing procedure were analyzed. The log image segmentation method was studied using Otsu's method,and the log image morphological filtering approach was introduced,based on which,the log image center line was determined using edge detection method. A center-line-based automatic log cutting method was then proposed and experimentally tested.

In this paper,with the help of Colibri color matching software,spectrophotometer and other instruments,a wood floor paint database was established. Preliminary experiments were made to study the computer color matching technology of wood floor paint. The results showed that the toner database could meet the requirements of color matching. The color deviation was between 3. 37-6. 73 according to tests on red oak flooring. The inhomogeneity of the wood color had a great influence on color measurement and the accuracy of computer color matching. Further experimental research was still needed to take into consideration the factory floor painting technology,the requirements on wood grain and the experience of veteran painters.

Based on the hot water softening treatment of the knots of Chinese fir and hardness test, slicing experiment on the Chinese fir timber of 140mm ×10mm ×2000mm is conducted, with the result showing that the Chinese fir features many knots and high hardness. Therefore, the timber must go through hot water softening treatment before slicing and at the same time, the wedge angle of a slicer must be increased. It is recommended that the wedge angle of a slicer should be 22 °. When the slice thickness is 1mm~2mm, the hot water softening treatment time is four weeks. When the slice thickness is 3mm~4mm, the hot water softening treatment time is six weeks.

The automatic measurement of trunk curvature is essential for safe and efficient operation of debarking and chipping combined machine.Customized for the characteristic of trunk image,an automatic trunk curvature measurement and control method is presented in this paper.The trunk curvature can be measured and calculated automatically by means of automatic image acquisition and image processing technology.The data can be transferred to the control system of bend-cutting unit of the combined machine.

A self-propelled combined debarking and chipping machine is studied and designed and it mainly consists of waling, peeling, chipping and auxiliary supporting devices. With a diesel generator providing power, the requirements for infeed, peeling and chipping operations are met. The machine is suited to be used in forest areas and can process small-diameter trees and logging residues into high-quality bark-free chip, which can not only save labor cost but also reduces transport cost.

为了满足多种型号PLC共存的工业控制系统集成要求,研究了面向PLC的OPC服务器快速开发方法,给出了基于工具包的面向PLC的OPC服务器的详细设计与实现方法.设计、开发了用于FMS控制的PLC的OPO服务器,运行结果表明该服务器符合OPC接口规范要求.

为了满足制造单元快速重构要求,本文在对可重构制造单元的控制结构要求,以及OPC技术深入分析研究的基础上,将OPC技术引入到制造单元控制中,提出了基于OPC的可重构制造单元控制结构；建立了可重构制造单元控制系统软件架构,并对OPC服务器、功能组件、设备控件、单元开控制器等进行了详细设计；最后,利用所开发的原型系统,构建了FMS控制系统,运行结果表明该系统运行可靠,并满足快速重构要求.

For the demand of wear particle detection,wear particle multi-focus image fusion method was studied based on color space conversion and wavelet analysis theory.The low frequency fusion coefficients from the clear regions were selected based on the characteristic factor of neighborhood gradient.The high frequency fusion coefficients were selected based on absolute value maximum by establishing new high frequency sub-band.The effects of wavelet base and decomposition layer on wear particle image fusion were studied respectively.The results show that better fusion effect can be obtained by using the wavelet base of db4,sym4 or bior2.4 when the decomposition layer is five.